The main features you are looking for in a tyre are:
- puncture resistance – many tyres now have a puncture resistant layer beneath the rubber. These can make a considerable difference to the number of punctures you get. In the year of my end to end I cycled about 9,000 miles on these tyres and suffered 3 punctures (none on the end to end itself). Of those, two were caused by nails, which no amount of armouring would have stopped.
- grip in wet weather – some rubber compounds and tread patterns are more grippy in wet, muddy conditions than others. A slick racing tyre will not offer the same sure grip as a heavily threaded mountain bike tyre.
- rolling resistance – this is how much energy is lost through friction between the tyre and the road surface. Generally the smoother the thread and the narrower the tyre the less the rolling resistance will be. Hence slick 19mm racing tyres will have low rolling resistance and take less effort to ride on.
- weight – the heavier the tyre the more weight you have to carry across the country. Also, due to something called rotational mass, the less wieght you can have near the rim of your wheels the less effort you will need to accelerate up to speed everytime you have to slow down or stop.
- comfort – the thicker the tyre the more suspension there is between you and the road surface, hence the more comfortable the ride. A 19mm racing tyre, pumped to 120psi, does not offer ultimate comfort!
As you can see some factors are almost the opposite of others and you will have to balance up what is important to you and your ride. There are tyres whose manufacturers claim they offer everything, but then so would I if I was trying to sell one.
The life expectancy of tyres varies enormously but I would expect one to last about 2,000 miles. So check them for wear before you go – depending on your route you may have several hundred miles to cover and don’t really want to have to change them half way. I usually put new tyres on my bike before the start of a tour and then put the old ones back on once those were past their useful life.